Involuntary commitment, civil commitment, or involuntary hospitalization/hospitalisation is a legal process through which an individual who is deemed by a qualified agent to have symptoms of severe mental disorder is detained in a psychiatric hospital (inpatient) where they can be treated involuntarily. This treatment may involve the administration of psychoactive drugs, including involuntary administration. In many jurisdictions, people diagnosed with mental health disorders can also be forced to undergo treatment while in the community; this is sometimes referred to as outpatient commitment and shares legal processes with commitment.

Criteria for civil commitment are established by laws which vary between nations. Commitment proceedings often follow a period of emergency hospitalization, during which an individual with acute psychiatric symptoms is confined for a relatively short duration (e.g. 72 hours) in a treatment facility for evaluation and stabilization by mental health professionals who may then determine whether further civil commitment is appropriate or necessary. Civil commitment procedures may take place in a court or only involve physicians. If commitment does not involve a court there is normally an appeal process that does involve the judiciary in some capacity, though potentially through a specialist court.

Historically, until the mid-1960s in most jurisdictions in the United States, all committals to public psychiatric facilities and most committals to private ones were involuntary. Since then, there have been alternating trends towards the abolition or substantial reduction of involuntary commitment, a trend known as deinstitutionalisation. In many currents, individuals can voluntarily admit themselves to a mental health hospital and may have more rights than those who are involuntarily committed. This practice is referred to as voluntary commitment.

In the United States, a long-term or indefinite form of commitment is applied to people convicted of some sexual offences.